The present invention relates to a memory card, and more particularly to a memory card in which program data are downloaded and stored on a nonvolatile memory.
Memory cards are employed for reading/writing information with digital devices such as digital cameras, PDAs, portable audio devices, cellular phones, and personal computers. Two types of chips, which are a flash memory and a controller, are mounted on a memory card. Flash memories mounted on memory cards have recently increased in capacity to the extent that they are becoming capable of storing large amounts of data. At the present moment, however, memory cards only exchange data with digital devices. In some IC cards, application programs can be downloaded and executed. However, the capacity of their nonvolatile memory for program storage is much smaller than the capacity of flash memories mounted on memory cards.
It is an object of the present invention to provide a memory card whose circuit scale can be reduced.
A memory card according to the present invention includes a first nonvolatile memory, a second nonvolatile memory, and a separating portion. The first nonvolatile memory has a predetermined erase unit. The second nonvolatile memory has an erase unit that is larger than the erase unit of the first nonvolatile memory. The separating portion separates at least the portion of the program data that are downloaded onto the memory card that has the possibility of being rewritten, and stores the separated portion onto the first nonvolatile memory and stores the remaining portion onto the second nonvolatile memory.
According to this memory card, when the downloaded program is executed, program data are rewritten only in the first nonvolatile memory and not rewritten in the second nonvolatile memory. Thus, by rewriting variables or the like in the first nonvolatile memory, which has a small erase unit, the required buffer size is smaller than if the process were performed in the second nonvolatile memory, which has a large erase unit, and the circuit can be made small in scale.
Also, the size of the data that are temporarily buffered for rewriting is smaller in the first nonvolatile memory than in the second nonvolatile memory. Consequently, the buffering time for rewriting can be kept shorter than if the rewriting process were performed in the second nonvolatile memory, and the amount of time required for rewriting can be shortened.
Moreover, data security is improved because the program data that are downloaded are separated and stored on the first nonvolatile memory and the second nonvolatile memory.